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J. B.' FRANKLIN.

Drawing-Board.

117 761. Patented August a, 1871.

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UNITED STATES JOHN B. FRANKLIN, OF NEW YORK, N. Y.

IMPROVEMENT IN DRAWING-BOARDS.

Speeication forming part of Letters Patent No. 117,761, dated August 8,1871.

To all ywhom it may concern: 1

Be it known that I, JOHN B. FRANKLIN, of the city, county, and State ofNew York, have invented a new and Improved Drawing-Board, and I dohereby declare that the following is a full, clear, and exactdescription thereof, which will enable others skilled in the art to makeand use the same, reference being had to the accompanying drawingforming part of this specification, in which the drawing represents aperspective view,partlyin section, of my improved drawin g-board.

The object of this invention is to provide drawing-boards with concealedmetallic stays or braces, whereby they will be prevented from warpingand retained smooth when shrinking. The difficulty to be overcomeconsists chiefly in the necessity of keeping metal away from the surfaceof the board in order to permit the application of drawing-pins. Myinvention consists in interposing metallic strips or braces between thehard-wood edge-pieces and the board in the dovetail grooves at the endsof the board. The invention ccnsists also in the use, for large boards,of central hard-wood cross-pieces lined at the edges with L-shapedstrips of metal.

A in the drawing represents the body or main portion of thedrawing-board. 'B B are the hardwood edge-pieces applied to the ends ofthe board by being dovetailed thereto, as shown. O O are strips of dator oval metal interposed between the contiguous faces of the pieces Band board A, so that they rest in the grooves of the latter, being thusconcealed and not interfering with the surface of the board. The narrowmetal strips O, being on edge Vwithin the board, eectually resist thewarping of the same and keep it straight while it contracts or shrinks.The

edge-pieces are not glued or screwed to the board, and can be shifted tokeep their ends always flush with the lower edge of the board.l Longboards I propose to strengthen by means of a central cross-piece, D, ofhard wood, let into a groove at one face of the board A, and extendingfromthe upper to the lower edge of same. Against the edges of this pieceD, I place metal strips E E, L-shapedin cross-section, or of equivalentform, but not reaching to the surface of the board, as shown. Thesestrips E, together with the cross-piece D, serve to stiften the board atthe part where otherwise it would be most apt to bend. In order tocounteract the weakening eifeet of the groove cut into the board for thereception of the cross-piece D, I propose to glue a piece, F, of hardwood against the upper edge of the board.

It will be observed that the entire board has :nothing but wood on bothsurfaces, and can, therefore, be used on either side. The metal strips Oare or may be screwed to the edgepieces B, and the strips E may also besimilarly attached to the cross-piece D.

Having thus described my invention, I claiin as new and desire to secureby Letters Patent- 1. The metallic strips O O, applied to adrawing-board between the edge-pieces B B and the body of the same,substantially as herein shown and described. f

2. The hard-wood cross-piece D, let into the grooved face ofthedrawing-board and combined with the metallic strips E, substantially asherein shown and described.

JOHN B. FRANKLIN.

Witnesses:

GEORGE W. MABEE, T. B. Mosi-IER.

